The one at Garryntinodagh in County Wexford is different: it has all but vanished from the surface, leaving behind only a shadow in the crops above it. This kind of trace is known as a cropmark, a phenomenon that occurs when buried features such as ditches retain more moisture than the surrounding soil, causing the vegetation above them to grow differently, and visibly so, from the air.

What the aerial photographs reveal is a circular enclosure roughly fifty metres in diameter, defined by a single fosse, the term for the ditch that typically surrounds an Irish rath. Ringforts are among the most common archaeological monuments in Ireland, generally dated to the early medieval period, roughly the fifth to the twelfth centuries, and understood to have served as enclosed farmsteads for individual family groups. Most were defined by one or more earthen banks thrown up from the spoil of the surrounding ditch. At Garryntinodagh, the low-lying landscape has apparently allowed centuries of cultivation and soil movement to level whatever upstanding remains once existed, leaving the fosse to do the quiet work of preservation underground. The cropmark was first captured in an aerial photograph taken in 2004, and confirmed in the Ordnance Survey Ireland series taken the following year.